The invention relates generally to methods and apparatus for measuring magnetic field strengths and field uniformity of permanent magnets.
As is known in the art, a magnetometer is an instrument for measuring the strength and uniformity of a magnetic field. A prior art measurement technique involves the use of Hall effect probes operating with direct or differential readouts to measure magnetic field strengths and the uniformity of such magnetic field strengths. The magnetic field strength is measured by the amount of current produced by the Hall effect probe when such probe is inserted into a magnetic field being measured. The Hall effect is defined in accordance with the equation F=eBv; where F=the force; e=the electric charge; B=the magnetic field; and v=the velocity of the electron charge. The Hall effect technique is based on the phenomenon which occurs when a thin sheet of metal or semiconductor with an electric current flowing along its length is placed at right angles to a magnetic field. An electromotive force is developed which is at right angles both to the direction of the magnetic field and the electric current. The Hall coefficient associated with the Hall effect takes place when the electromotive force results in a transverse potential gradient in a conductor or semiconductor. While such probe may be accurate in measuring magnetic field strengths and uniformities in some applications, in other applications such probes do not provide the requisite accuracy.